With the increase in track density of hard disk drives in recent years, interference between adjacent tracks has become a matter of concern. In particular, reducing side write due to the magnetic field fringe effect of the recording head is an important issue. A discrete track recording (DTR) medium, in which recording tracks are physically separated, can reduce side erase during recording and side read, in which crosstalk from an adjacent track occurs, during reproduction, thereby increasing the density in the cross-track direction. This makes the DTR medium promising as a high-density magnetic recording medium. In addition, a bit-patterned medium (BPM) physically divided in the bit direction has been proposed as a high-density magnetic recording medium capable of suppressing medium noise and thermal decay, in which recorded data disappears at room temperature.
Since the DTR medium and BPM are manufactured by means of the etching processing technique, the manufacturing cost may higher than normal. Therefore, the following method has been proposed. That is, fine patterns obtained by electron beam (EB) lithography are transferred to a master, and a mother (or master) stamper such as an Ni stamper is duplicated from the master by electroforming. The mother stamper is then set in an injection molding machine, and resin stampers are mass-produced by injection molding. The DTR medium or BPM is manufactured by ultraviolet (UV) curing imprinting using the resin stamper.
When manufacturing the DTR medium or BPM, it is necessary to transfer fine patterns 1/10 or less the size of patterns formed on optical disks. When patterns are made smaller as the recording density increases, however, it often becomes difficult to duplicate the mother stamper from the master by electroforming. Therefore, demands for a high releasability and high durability of the mother stamper are increasing.